The goal of this-project is to characterize the recently isolated human orthologue of the novel gene MYG1, and to test whether aberrations within its genomic locus are associated with skin and other cancer types. We have originally isolated MYGl from mouse autonomously growing melanocytes. The product of this gene is highly conserved along evolution line from yeast to human. Initial results reveal a high level expression of MYG1 in heart, liver, and induced expression in proliferating melanocytes. MYG1 protein localizes to nucleus in growing and to cytoplasm and possibly mitochondria in confluent melanocytes. We hypothesize that MYG1 may be associated with the regulation of cells transition between proliferating and quiescent states, and therefore, with differentiation and growth processes. The human MYG1 gene will be analyzed by western analysis for expression levels and patterns of isoforms and by immunohistochemistry for subcellular localization, in relation to cell density and growth-state, in melanocytes and melanoma cells. The human MYG1 gene was localized to 12q13, a chromosomal region in which aberrations were found in the genome of melanoma, lymphoma and other types of cancer patients. We will examine whether some of these aberrations involve the human MYG1 gene locus. We will use hybridization in wells as a screening method followed by Southern confirmation. To summarize, the initial results indicate that MYG1 is associated with cell growth, and therefore possibly with malignancy. The high conservation along evolution suggests a fundamental cellular function and the elevated expression in heart and liver points to an essential function of MYG1 in these organs, and possible linkage to disease and defects in case of malfunctioning MYG1.